hwo to pass the form2 listbox selected item to form 1 in data grid view column

On click of button u should store selected list box value in session and in second page u should check session then bind value in grid .

In the form you want the data to go to, create another constructor there that takes a parameter. For example the name of the second form in Form2 and inside the 1st form, let's say Form1, you have a button click event where you choose a value and when you a button the other form shows.

//Inside the 1st form - Form1
public void Button1_Click(Object sender, EventArgs e)
{
    string value = DropDownList.SelectedValue;
    Form2 f = new Form2(value);
    f.Show();
}

In the Form2 class you must need a custom constructor to accept this value, so lets create that. Also, you need probably a global variable or a property so that value is known throughout the class. Let's use a global variable in this example to keep it simple.

//Global variable
public readonly string _value; //remove readonly if you want to change the variable value.

public Form2(string value)
{
    _value = value;
}

Then use the _value however you need to include it in your datagridview.